1. Field of the Invention
The present invention relates to an image recording apparatus.
2. Description of the Related Art
A conventional color image recording apparatus such as a printer, a copying machine, and a facsimile machine is equipped with print engines for yellow, magenta, cyan, and black, an intermediate transfer belt, LED heads, a primary transfer roller, a secondary transfer roller, and a fixing unit. The intermediate transfer belt runs along a row of the print engines. The LED heads are provided to corresponding print engines so that each LED head illuminates the surface of a photoconductive drum of a corresponding print engine to form an electrostatic latent image on the surface. The primary transfer roller is disposed with the intermediate transfer belt between the primary transfer roller and the respective print engines, so that color toner images on the respective photoconductive drums are transferred onto the intermediate transfer belt in registry. The secondary transfer roller transfers the toner images on the intermediate transfer belt onto a print medium such as paper or OHP sheet. The fixing unit fixes the color toner images on the print medium.
However, with the aforementioned conventional image recording apparatus, pages of print medium advanced to the print engines are very closely spaced, thereby increasing the throughput in each printing operation. The toner images are formed on the intermediate transfer belt at predetermined intervals in accordance with the spacing of the print medium. If the pages of print medium cannot be advanced in succession, e.g., when the print medium is jammed or paper cassettes run out of print medium, the toner images formed of one or more colored toners remain left on the intermediate transfer belt. Therefore, the toner images remaining on the intermediate transfer belt have to be removed before printing is resumed after the paper cassettes are replenished with print medium, and then the same toner images have to be formed again on the intermediate transfer belt. This implies that toner images previously formed on the intermediate transfer belt but not transferred onto a print medium are wasted.
Moreover, when a paper cassette runs out of print medium in the middle of a printing job, print medium should be fed from another paper cassette that holds print medium of the same size. However, the print medium may not be accurately positioned relative to the toner image on the intermediate transfer belt due to the fact that the print medium has to travel through a transport path of a somewhat different length. Thus, the toner images formed on the intermediate transfer belt have to be removed and new toner images have to be formed on the intermediate transfer belt. This also results in waste of toner.
The present invention was made to solve the aforementioned problems and an object of the invention is to provide an image recording apparatus that reduces waste of toner.
An image forming section forms images, which are transferred by a transfer section onto a primary medium from the image forming section. A medium cassette holds a stack of print medium. A remaining-medium detector detects the number of pages of remaining print medium held in the medium cassette. The images on the primary medium are transferred onto a print medium fed from the medium cassette. A controller changes a timing at which the image forming section forms the images, the timing being changed in accordance with the number of pages of remaining print medium.
The controller causes the image forming section to form the images at first timings when the medium cassette holds pages of the print medium of more than a reference value. The controller causes the image forming section to form the images at second timing when the medium cassette holds pages of the print medium equal to or less than the reference value. The second timings are delayed relative to the first timings so that the images are formed at greater distance intervals on the primary medium when the images are formed at the second timings than when the images are formed at the first timings.
The controller changes the timing when the medium cassette holds pages of the print medium of equal to or less than a reference value. The timing is changed after the controller determines that the medium cassette holds at least one page of print medium.
The medium cassette is one of a plurality of medium cassettes each of which has the remaining-medium detector. When a first medium cassette of the plurality of medium cassettes holds pages of the print medium more than a reference value during a printing job, the controller feeds the pages of the print medium from the first medium cassette to the transfer section. When the first medium cassette becomes empty of the print medium in the middle of the printing job, the controller feeds the print medium from a second medium cassette of the plurality of medium cassettes to the transfer section instead of the first medium cassette. The second medium cassette holds a stack of print medium therein.
The controller causes the image forming section to form the images at first distance intervals when the print medium is fed from the first medium cassette that holds pages of the print medium of more than the reference value. The controller causes the image forming section to form an image in such a way that an image for a final page fed from the first medium cassette and the image for the first page fed from the second medium cassette are spaced apart by a second distance interval. The second distance interval is longer than the first distance interval. The controller causes the image forming section to form the images at the first distance intervals when the controller feeds pages of the print medium from the second medium cassette after the first page of the stack of print medium is fed from the second medium cassette.
The first medium cassette holds pages of first print medium having a first size and the second medium cassette holds pages of second print medium having a second size, the first size being smaller than the second size.
The controller causes the image forming section to form the images at different distance intervals in accordance with the number of pages of print medium that remains in the medium cassette.
The controller causes the image forming section to form the images at first distance intervals when the medium cassette holds pages of the print medium more than a reference value. The controller causes the image forming section to form the images at second distance intervals when the medium cassette holds pages of the print medium equal to or less than the reference value, the second distance intervals being longer than the first distance intervals.
The controller causes the image forming section to form the images at distance intervals longer than a difference between a first distance from the image forming section to a secondary medium and a second distance from the medium cassette to the secondary medium.
The medium cassette is one of a plurality of medium cassettes each of which has the remaining-medium detector. When a first medium cassette holds pages of the print medium of more than a reference value, the controller feeds the print medium from the first medium cassette. When the number of pages of the print medium in the first medium cassette decreases below the reference value in the middle of a printing job, the controller feeds the print medium from the second medium cassette. When the controller feeds the print medium from the second medium cassette instead of from the first medium cassette, the controller causes the image forming section to form images at different distance intervals. The distance interval is changed in accordance with a difference in medium transport path between when the print medium is fed from the first medium cassette and when the print medium is fed from the second medium cassette.
The controller causes the image forming section to form the images at first distance intervals when the controller feeds pages of the print medium from the first medium cassette and the first medium cassette holds the print medium of more than the reference value. The controller causes the image forming section to form an image in such a way that an image for a final page fed from the first medium cassette and the image for the first page fed from the second medium cassette are spaced apart by a second distance interval. The second distance interval is longer than the first distance interval, Further, the controller causes the image forming section to form the images at the first distance interval when the controller feeds pages of the print medium from the second medium cassette after the first page of the stack of print medium is fed from the second medium cassette.
The first medium cassette holds pages of first print medium having a first size and the second medium cassette holds pages of second print medium having a second size, the second size being larger than the first size.
The image forming section is one of a plurality of image forming sections, the plurality of image forming sections forming images in registration with one another.
The controller causes the image forming sections to form the images at distance intervals larger than a difference between a first distance and a second distance. The first distance is a distance from an image forming section most upstream in a transport path of the primary medium to the transfer section. The second distance is a distance from the medium cassette to the transfer section.
The image forming sections are arranged to configure a tandem type image recording apparatus.
The image recording apparatus further comprises a display that indicates that the number of pages in the medium cassette is less than a reference value.
The primary medium is a transfer belt.
The primary medium is a transfer drum.
The medium cassette includes a medium-holding member that holds the stack of the print medium thereon and takes up a different position in accordance with the number of pages of the print medium remaining in the medium cassette. The detector detects the number of pages of the print medium held in the medium cassette in terms of a position of the medium-holding member.
The medium-holding member has a reflective member, so that the detector detects the number of pages of the print medium held in the medium cassette in terms of a position of the medium-holding member.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.